Centrifugation of adipose tissue aspirate causes endothelial cell enrichment

A recent study demonstrated that centrifuging fat causes a density gradient where progenitor cells (ASCs) show a higher concentration in the lower part of the fatty cylinder. Furthermore, it was shown that fat grafts of this part have a higher survival rate and it was hypothesized that this is due to higher concentration of ASCs. Since ASCs are only a part of the stromal vascular cell fraction, we hypothesized that the main reason for a higher take of autologous fat grafts might not solely be due to ASCs but other cell types as well. We aimed to verify which cell types exactly are concentrated in the stromal vascular fraction of the lower part of the fatty cylinder. Human adipose tissue from 10 female patients was subjected to a washing procedure to remove blood cells and cells were mechanically released to assure homogeneous sample size and quality. Subsequently, samples were divided into three groups. 1) Sedimentation, 2) Mild centrifugation, and 3) Harsh centrifugation. Stromal vascular cells (SVCs) were isolated by filtration and centrifugation from each processed cylinder. SVCs were simultaneously stained and analyzed by flow cytometry to determine the cell types present. Our results show that out of all stained cells in the stromal vascular fraction, only endothelial cells were enriched in the lower part; remarkably, ASCs were not enriched, in contrast to results of previous studies.